[WIP/DNM]: feat(kobo): enable syncing of annotations to Hardcover

[black-dragon74]

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Actively being tested and updated. DO NOT REVIEW.

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💬 Additional Context (optional)

[black-dragon74]

@acx10 @balazs-szucs Need a little help here. In my testing, I am able to sync the annotations to hardcover.

Still, the device always fails with "sync failed, try again later".

Pretty sure I am messing something up when proxy-ing the request to Kobo. Any pointers?

This feature is almost complete (in its initial form), just this once thing needs ironing out.

If it helps, I have a KLC, any way I can see why the sync fails?